Biogen (BIIB) Stock Forecast & Price Target

Biogen is supported by a durable cash-generating base, with its MS franchise still contributing 40% of 2025 revenue and Roche-linked CD20 collaboration revenue adding 19%, while newer assets like Leqembi, Skyclarys, Zurzuvae, Spinraza, and Qalsody diversify the mix. Its positive outlook is also anchored in improving growth visibility: Q2 total revenue reached $2.74B, Leqembi rose 15% Y/Y to $511MM in 2025, and Skyclarys grew 36% Y/Y to $520MM, helping offset the expected long-term erosion of legacy MS sales. Finally, the pipeline and business development strategy offer meaningful upside, with litifilimab Phase III SLE data expected later in 2H26, positive Phase II CLE data, and the Apellis deal adding Syfovre and Empaveli to strengthen the 2026 and beyond growth profile.

Biogen is facing a structurally weakening revenue base, as its MS franchise still accounts for 40% of total revenue in 2025 while the segment is already in mid-teens decline ex-Vumerity and Tecfidera fell 53.0% Y/Y in Q2:26. Although newer assets such as Spinraza, Leqembi, Skyclarys, Zurzuvae, and Qalsody provide diversification, much of the growth is still dependent on collaboration economics and launch execution, with Roche CD20 agreements representing 19% of 2025 revenue. The outlook remains pressured by intense competition, genericization, reimbursement uncertainty, and pipeline risk, while higher R&D spend and approximately ($0.85) FY26 EPS dilution from the Apellis acquisition further weigh on fundamentals.